This invention relates to a method of treating a silicon single crystal ingot used in the manufacture of a semiconductor device, and more particularly to a method of treating a silicon single crystal ingot to suppress the occurrence of lattice defects in the silicon single crystal during the manufacture of a semiconductor device.
Silicon is a most important material of a semiconductor device. Recent development of a large scale integrated circuitry has come to demand a silicon single crystal having a more perfect crystal structure. Lattice defects of a silicon single crystal such as stacking faults, dislocations and precipitates very adversely affect the properties and performance of a semiconductor device manufactured from the silicon single crystal. Stacking faults in particular exert very harmful effects on a semiconductor device. For example, the stacking faults increase leakage current at P-N junctions, or reduce the period during which carriers are stored in a charge-coupled device. As mentioned above, lattice defects of a silicon single crystal undesirably cause many disqualified semiconductor devices to be produced, eventually decreasing the yield thereof.
The above-mentioned lattice defects are formed during the manufacture of a semiconductor element from a silicon single crystal ingot. The occurrence of stacking faults in particular is largely affected and accelerated by the presense of impurities such as oxygen, carbon and heavy metals which are unavoidably carried into a silicon single crystal ingot during its growth. The stacking faults tend to arise prominently when the silicon single crystal undergoes oxidation treatment at high temperature.
To date, some processes have been proposed to suppress the occurrence of the lattice defects. One prior art process is to generate a mechanical strain field on the back side of a wafer cut out of a silicon single crystal ingot, thereafter the wafer is heat treated at high temperature. However, this conventional process which treats the respective wafers is very troublesome, and moreover has to be carried out with respect to all the semiconductor-manufacturing steps in which the stacking faults are likely to take place. Therefore, this conventional process for treating the wafer makes the manufacture of a semiconductor device very inefficient.